Kendra Harrison broke the 28-year-old 100 metres hurdles world record at the Olympic Stadium on Friday - just two weeks after failing to make the United States team for the Rio Olympics.
The 23-year-old stormed over the barriers to cross the line in 12.20 seconds at the Muller Anniversary Games, beating Bulgarian Yordanka Donkova's mark by one hundredth of a second.
She collapsed into floods of tears at the finish at her achievement.
It came just a fortnight after she could only finish in sixth place at the US trials, seeing her Olympic hopes crushed.
She said on the eve of this event the only thing that could help make up for that disappointment was to break the world record - although few could have predicted it coming quite so soon.
"I'm just so full of emotions," said Harrison, whose previous best was the 12.24 she ran in May.
"Not making that Olympic team, I knew I had to come out here and show the world I still had it in me.
"My coach has been telling me since day one that I had it in me. I still have a few weeks to go so I am going to try and lower that time."
Harrison received a cheque for 50,000 US Dollars (€45,500) for the record.